Ophthalmic Surgery Notes

The Orbital Cavity

  • The orbital cavity is formed by several bones:
    • Frontal bone
    • Optic foramen
    • Ethmoid bone
    • Superior orbital fissure
    • Sphenoid bone
    • Zygomatic bone
    • Lacrimal bone
    • Maxilla
    • Infraorbital foramen
    • Inferior orbital fissure

The Globe

  • Key structures:
    • Cornea (transparent)
    • Pupil
    • Iris
    • Lens
    • Optic disc
    • Optic nerve
    • Anterior chamber (contains aqueous humor)
    • Posterior chamber (contains aqueous humor)
    • Ciliary body
    • Vitreous
    • Retina
    • Choroid
    • Sclera
    • Visual axis
    • Lacrimal caruncle
    • Fovea
    • Macula lutea
    • Central artery and vein
    • Lower lid

Key Anatomical Structures and Their Functions

  • Conjunctiva:
    • Thin, transparent mucous membrane that lines each eyelid and covers the sclera.
    • Divided into palpebral and bulbar regions.
  • Cornea: Clear tissue layer overlying the front of the eyeball.
  • Sclera:
    • Thick, white, fibrous tissue that encloses about three-fourths of the eyeball.
  • Choroid:
    • Vascular pigmented layer beneath the sclera.
    • Prevents light reflection within the eyeball.
  • Ciliary Body:
    • Extension of the choroid located at the periphery of the anterior choroid.
    • Contains smooth muscle to which the suspensory ligaments are attached.
  • Retina: Innermost layer of the posterior globe.
  • Lens:
    • Lies directly behind the iris; a biconcave, clear structure encompassed by a transparent capsule.
    • Held in place by suspensory ligaments and focuses images projected onto the retina.
  • Anterior Chamber:
    • Divided into two chambers by the iris.
    • Lies directly in front of the iris.
  • Posterior Chamber: Directly posterior to the iris but anterior to the lens.

Refraction and Accommodation

  • Refraction: Bending of light rays through a transparent medium.
  • Focal Point: Location where light converges.
  • Accommodation: Process of focusing.

Factors Affecting Eye Chambers

  • Damage can occur due to:
    • Irregularities of the epithelial surface.
    • Retinal and choroid diseases.
    • Eye tissue abnormalities.
    • Orbital structures.

Preoperative Preparation

  • Creating a Relaxing Environment:
    • Essential due to the possibility of blindness as a complication.
    • Addresses patient's fear and lack of control.
  • Conscious Sedation: Procedures commonly done under conscious sedation.
    • Patient remains awake and must be aware of this.
    • Patients must override the normal reflex to pull away.

Verification of Operative Site

  • Responsibility: The entire surgical team is responsible for verifying the operative eye.
  • The Joint Commission: Recommends the surgeon mark the skin near the operative site.
  • Confirmation: Check with the patient for the correct procedure and correct site.

Patient Positioning

  • Position: Supine, with head stabilized in a donut.
  • Comfort: Ensure the patient is safe and comfortable with a pillow under the knees.

Prep and Drape

  • Contamination: The canthus of the eye is considered contaminated.
  • Draping:
    • Includes isolation of the hairline and nonoperative side.

Medications

  • Administration: Instilled or injected into the eye before, during, and after surgery.
  • Uses: Vary according to the type of surgery.
  • Labeling: Medications must be labeled as soon as they are on the field.
  • Identification: Identified and acknowledged with the surgeon.
  • Documentation: Recorded on the operative report.

Counts

  • Items to Count:
    • Sutures (needle tips are very small).
    • Blades
    • Weck Spears

Anesthesia

  • Regional Anesthesia: Many procedures are done with regional anesthetic and monitored sedation.
  • General Anesthesia: Pediatric patients are typically given general anesthesia.
  • Retrobulbar Block: A type of regional anesthesia used in eye surgery.

Cutting Instruments

  • Graefe cataract knife
  • Keratomes (disposable)
  • Razor fragments
  • Diamond knife
  • Beaver blades
  • No. 15 knife blade

Forceps

  • Bishop-Harmon iris forceps
  • Desmarres chalazion forceps
  • Colibri Forceps
  • Non tooth forceps

Other Instruments

  • Bowman probe
  • Caliper
  • Needle holder

Retractors

  • Scleral hooks: For scleral retraction.
  • Kilner hook: Used in reconstructive surgery.
  • Desmarres lid retractors
  • Iris retractor
  • Eye speculum

Special Equipment

  • Electrosurgical unit (ESU)
  • Phacoemulsifier/Vitreoretinal systems
  • Eye sponges
  • Sutures
  • Ophthalmic dressings
  • Microscope
  • Lasers

Microscope

  • Magnification: Surgeon’s field of vision is magnified.
  • Limited Scope: Area of vision is very limited.
  • Surgeon's Focus: Surgeon cannot look away from the field.
  • Scrub Nurse's Role: Scrub must prepare ahead for each step of the procedure and prevent movement of the microscope.
  • Adjustment: The microscope should be adjusted for height and placement over the patient by the surgeon just before scrubbing.
  • Draping: The microscope will require draping or sterile knobs; this is performed after the patient has been prepped and draped.

Surgical Procedures

  • Eye Muscle Surgery - Strabismus
  • Chalazion Excision: Nodal tissue arising from a sebaceous gland is excised from the tarsal plate.
    • A chalazion is an inflammatory, benign growth that originates in a sebaceous gland of the eyelid.
  • Nasolacrimal Duct Probing/Stenting
  • Dacryocystorhinostomy (DCR)
  • Excision of a Pterygium: The pterygium membrane is surgically removed to prevent loss of vision.
  • LASIK (Laser In Situ Keratomileusis):
    • Anesthesia: The eye is anesthetized with topical eye drops.
    • Corneal Flap: The surgeon creates a corneal flap on the outer layer of the eye. It is cut and flipped open.
    • Laser Reshaping: An excimer laser is used to reshape the cornea.
    • Flap Replacement: The corneal flap is replaced.
    • Purpose: performed to shape the curvature of the cornea and correct a refractory problem.

Cataract Extraction

  • Definition: Removal of opaque lens (cataract).
  • Causes: Result of aging process, trauma, glaucoma, or medications.
  • Other Factors: May occur as a congenital anomaly, linked to radiation exposure (sunlight, X-ray radiation).
  • Phacoemulsification: Fragmentation of tissue through ultrasonic vibration.

Anterior Vitrectomy

  • Process: Removal of vitreous fluid from the anterior chamber.

Scleral Buckling

  • Purpose: Performed when the sensory layer of the retina becomes separated from the pigment epithelial layer.

Glaucoma

  • Types of Glaucoma
    • Primary angle-closure glaucoma
    • Open-angle or chronic glaucoma
    • Secondary glaucoma
    • Congenital glaucoma
  • Glaucoma Development
    • Drainage canal blocked; build-up of fluid
    • Increased pressure damages blood vessels and optic nerve

Iridectomy

  • Definition: The surgical removal of part of the iris.
  • Process: Cutting to create a hole in part of the iris.
  • Purpose: Hole allows fluid to flow normally.

Trabeculectomy

  • Definition: Surgical procedure used in the treatment of glaucoma to relieve intraocular pressure.
  • Process: Removing part of the eye's trabecular meshwork and adjacent structures.

Laser Treatment for Glaucoma

  • Mechanism: Use of the laser shrinks the collagen and stretches the canal of Schlemm, which expands the canal and increases drainage, thus reducing pressure.

Enucleation

  • Definition: Complete removal of the eyeball.
  • Steps in Enucleation:
    1. 360° peritomy performed
    2. Removal of the cornea
    3. Removal of ocular contents
    4. Incisions made in sclera for implant
    5. Orbital implant inserted
    6. Sclera and conjunctiva sutured over implant